cp's OEIS Frontend

A071898 CONTINUANT transform of A002487: 1, 1, 2, 1, 3, 2, ...

%I A071898 #15 Nov 10 2020 03:57:32
%S A071898 1,2,5,7,26,59,203,262,1251,4015,21326,46667,254661,810650,3497261,
%T A071898 4307911,25036816,104455175,756223041,2373124298,19741217425,
%U A071898 101079211423,727295697386,1555670606195,11616989940751,59640620309950,488741952420351,1525866477571003
%N A071898 CONTINUANT transform of A002487: 1, 1, 2, 1, 3, 2, ...
%H A071898 Alois P. Heinz, <a href="/A071898/b071898.txt">Table of n, a(n) for n = 1..400</a>
%H A071898 N. J. A. Sloane, <a href="/transforms.txt">Transforms</a>
%p A071898 b:= proc(n) option remember; `if`(n<2, n,
%p A071898       `if`(irem(n, 2, 'r')=0, b(r), b(r) + b(r+1)))
%p A071898     end:
%p A071898 a:= proc(n) option remember; `if`(n<0, 0,
%p A071898       `if`(n=0, 1, b(n)*a(n-1)+a(n-2)))
%p A071898     end:
%p A071898 seq(a(n), n=1..35);  # _Alois P. Heinz_, Aug 06 2013
%t A071898 b[n_] := b[n] = If[n < 2, n, r = Quotient[n, 2]; If[Mod[n, 2] == 0, b[r], b[r] + b[r + 1]]];
%t A071898 a[n_] := a[n] = If[n < 0, 0, If[n == 0, 1, b[n] a[n - 1] + a[n - 2]]];
%t A071898 Array[a, 35] (* _Jean-François Alcover_, Nov 10 2020, after _Alois P. Heinz_ *)
%Y A071898 Cf. A002487.
%K A071898 nonn
%O A071898 1,2
%A A071898 _N. J. A. Sloane_, Jun 10 2002